The present invention relates to a fixing apparatus and a fixing method applied to a color electronic copying machine, a printer, and a facsimile.
Fixing apparatuses of this kind include those comprising a heating roller and a pressure roller in pressure contact with the heating roller. In such fixing apparatuses, a toner image is melted and fixed on paper, by passing the paper onto which the toner image has been transferred through a nip part formed between the heating roller and the pressure roller, in a direction in which the toner image contacts the heating roller.
In the meantime, at the time of the above fixing, there are the cases where toner in the toner image transfers onto the heating roller due to unsatisfactory fixing. The apparatuses are structured such that the transferred toner is removed by being cleaned off by a cleaning member.
The cleaning member is positioned between a feeding roller and a winding roller, and an almost central portion of the cleaning member is pressed by a pressing roller and thereby is in pressure contact with the heating roller. The cleaning member is structured to be periodically fed by the feeding roller such that its new surface contacts the heating roller.
However, if the cleaning member is periodically fed, in the case of printing (copying) an image of a high printing rate, for example, a cleaning fault occurs, which causes an offset.
Further, conversely, in the case of printing (copying) an image of a low printing rate, the cleaning member is fed although it is still usable, which results in shortening the life of the cleaning member.
Therefore, it has been considered to control feeding of a cleaning member by determining the amount of spots on the cleaning member on the basis of a rate such as the printing rate, instead of periodically feeding the cleaning member.
However, in such a case, the amount of spots on the cleaning member are averaged and the averaged spot amount is determined, thus this method cannot deal with local spots and results in cleaning faults such as cleaning spots.
The present invention has been made in consideration of the above circumstances, and is aimed at providing a fixing apparatus and a fixing method which can reduce unnecessary use of a cleaning member and extend its life, and can obtain an optimum cleaning performance.
A fixing apparatus according to a first embodiment of the invention comprises a fixing device having a first roller and a second roller in pressure contact with the first roller, the fixing device fixing a developer image corresponding to an image onto a transferred medium by passing the transferred medium, onto which the developer image has been transferred, between the first roller and the second roller, in a direction in which the developer image contacts the first roller; a cleaning member which is in contact with the first roller, and removes the developer image adhered to the first roller at the time of fixing the developer image; a feeding device which feeds the cleaning member by a predetermined amount to change a contact position thereof to the first roller; a counter which counts the number of pixels of the image; and a control device which operates the feeding device to feed the cleaning member, on the basis of the number of pixels counted by the counter.
A fixing apparatus according to a second embodiment of the invention comprises a fixing device having a first roller and a second roller in pressure contact with the first roller, the fixing device fixing a developer image corresponding to an image onto a transferred medium by passing the transferred medium, onto which the developer image has been transferred, between the first roller and the second roller, in a direction in which the developer image contacts the first roller; a cleaning member which is in contact with the first roller, and removes the developer image adhered to the first roller at the time of fixing the developer image; a feeding device which feeds the cleaning member by a predetermined amount to change a contact position thereof to the first roller; a counter device which counts, by respective counters, the numbers of pixels of a plurality of regions, the regions being obtained by dividing a region of the image, whose number of pixels is to be counted, in an axial direction of the first roller; and a control device which operates the feeding device to feed the cleaning member, on the basis of counting of a predetermined number of pixels by any one of the counters of the counter device.
A fixing method according to a third embodiment of the invention comprises having a first roller and a second roller in pressure contact with the first roller, fixing a developer image corresponding to an image onto a transferred medium by passing the transferred medium, onto which the developer image has been transferred, between the first roller and the second roller, in a direction in which the developer image contacts the first roller; removing, by a cleaning member, the developer image which has contacted the first roller and adhered to the first roller at the time of fixing the developer image; feeding the cleaning member by a feeding device by a predetermined amount to change a contact position thereof to the first roller; counting the number of pixels of the image by a counter; and operating the feeding device to feed the cleaning member, on the basis of the number of pixels counted by the counter.
A fixing method according to a fourth embodiment of the invention comprises having a first roller and a second roller in pressure contact with the first roller, fixing a developer image corresponding to an image onto a transferred medium by passing the transferred medium, onto which the developer image has been transferred, between the first roller and the second roller, in a direction in which the developer image contacts the first roller; removing, by a cleaning member, the developer image which has contacted the first roller and adhered to the first roller at the time of fixing the developer image; feeding the cleaning member by a feeding device by a predetermined amount to change a contact position thereof to the first roller; counting, by respective counters, the numbers of pixels of a plurality of regions, the regions being obtained by dividing a region of the image, whose number of pixels is to be counted, in an axial direction of the first roller; and operating the feeding device to feed the cleaning member, on the basis of counting of a predetermined number of pixels by any one of the counters.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.